Transmission system



' A ril 1927.

' 5 I J. 'J. KUHN TRANSMISSION SYSTEM Filed Feb. 28. 1925 2.Sheets-Sheet 2 Patented Apr. 5, 1927.

UNITED STATES 1,623,480 PATENT OFFICE.

JOHN J. KUHN, OF ELIZABETH, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS,TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

I TRANSMISSION SYSTEM.

Application filed February 28, 1925. Serial No. 12,249.

This invention relates to systems for the distribution of musical andother programs ovcr wires, and more particularly to announcing circuitsassociated with such systems.

The object of the invention is to enable a supervising operator orannouncer .to make announcements simultaneously to all subscribersconnected to the system in the event that it is desired to callattention to special program features or to spread an alarm signal in anemergency.

The invention finds a particular application in what have been calledapartment house radio systems. In these systems,

which are described in the applicants co-' pending application, SerialNo. 648,938 filed July 2, 1923, broadcast radio programs are received ata central station, for example, in a hotel or apartment building, andafter detection and amplification are distributed by wire to subscribersreproducing instruments in the various apartments. Several programs maybe distributedsimultaneously by different wire circuits any one of whichmay be selected by the subscriber.

By means of the present invention the operator supervising the radioreception is enabled to connect all subscribers instrumentssimultaneously v to an announcing inicrophone regardless of anyconnection previously made by the subscriber.

In the detailed description which follows the nature and operation ofthe invention will be described in connection with a programdistribution system of this type. It is to be understood, however, thatthe invention is not limited to such systems. Other applications of theinvention will be evident from the description.

Figs. 1 and 2 of the accompanying drawings illustrate'in schematic formsystems embodying alternative forms of the invention.

In Fig. 1, PT,, PT and PT are three program trunks entering the centralstation and each carrying waves corresponding to separate programs. Inthe system illustratedselected radio broadcast programs are received byradio upon antennae such as 1 and are delivered to the trunks throughdetecting and amplifying systems such as 2. These translating systemsmay be of any well known type, and since they form no part'of thepresent invention they are illustrated only conventionally. Instead ofusing a radio link the program trunks may, if desired, be run directlyto the studios at which the programs originate.

The program trunks are connected to main bus-bars B and B, and B fromwhich circuits branch to the subscribers stations, three of the latterbeing indicated at S S and S The equipments at the subscriber stationare the same. One such equipment 5, as viewed in the drawing, theterminals of'the loud speaker are short circuited and the subscribers.line is closed through resistance 6 which is sufficiently large toprevent a short circuit of the system. In the other positions of theswitch resistances 6 and 7 cooperate to vary the current intensity inthe receiver so that, as the switch contact is moved step-by-step to theright, the received volume is progressively increased.

The announcers circuit comprises a microphone 8 located at the centralstation, an energizing battery 9, and a repeating coil 31 through whichthe microphone is connected to trunk line 10. Branch lines from trunk 10extend to each subscriber station and terminate in front contacts 11 and12' of relays such as 13. The relays 13 at each station are connected inmultiple to a common line 14 in which is included battery15- and key 16the latter being under the control of the operator or announcer. Thesubscribers telephone is connected to armatures 17 and 18 of relay 13and normally through back contacts 19 and 20 to the volume controlswitch in the program line.

l/Vith this arrangement the operator or announcer is enabled by closingkey 16, and thereby operating relay 13, to transfer the connections ofall of the subscribers telephones to the announcing trunk line 10.Further, since the announcing line is connected bythe operation of therelays 13 directly to the telephone instrument terminals, closure of theswitch 16 connects the operators announcing circuit with each stationbattery receiver regardless of the condition of the An. additionalcontact 22 on this switch serves to close acircuit through battery 15which is applied. to theline when the line is connected to .theannouncers circuit. Speech currents are-prevented entering the circuit,which is bridged across the lineby choke coils 123 and the batterycurrentis prevented entering the repeating coil 11 of the announcerscircuit by line condensers 24.

One of the-subscribers stations is shown in detailed schematic at S,'.The circuit arrangements are similar to those of the sta tion S of Fig.1, but the operating winding of the relaylB is bridged acrosstheincoming line connected to program trunk PT instead of being served by aseparate line. In addition line condensers 25 are provided to confinethe direct current foroperating the relay to the relay circuit.

In the normal operation of the system the switch 21 is thrown to itsleft hand position whereby the-incoming program is delivered to thetrunk-PT and thence through the connected branch lines to thesubscribers" sets. The relay 13 is normally deener-- gized and thetelephone receiver 3 is connected through the back contacts of innerarmatures .17 and 18 to the terminals of volume control switch 5 andthence through selecting switch 4 to such one of the incoming'lines asmay be selected by the subscriber.

The line condensers 24 and 25 add their impedances to the line andhence, to maintain a high quality of transmission, they should be oflarge capacity. For analogous reasons the im edances of rela 13 andchoke coils 23 shoulc be large.

-\Vl1en the central station operator, desiring to make an announcement,throws swltch --2ltoits right hand position battery is applied throughtrunk PT and, through the connected branch lines. to the control relays'13. "At each subscribers station the energizing of relay 13 causes thetelephone receiver 4 to be connected through the frontcontacts o'farmatures 17'and 18 to the terminals ofv the'incommg line connected totrunk PT which in this arrangement now corresponds to the announcerscircuit 10 of Fig. 1. At

the same time the connections between switch 4 and volume control switch5 are broken at the back contacts of additional armaturcs 29 and 30.This prevents the volume control switch acting as a shunt on thetelephone receiver as it might'in the event that the subscribers werealready connected to the incoming branch line from program trunk PT,,and so ensures that an announcement or alarm signal will he heard.

What I claimed is:

1. In a program distributing system, a. central station, an incomingprogram trunk terminating thereat, a plurality of subscribers stationseach including a signal reproducing instrument, lines for connectingsaid reproducing instruments to said trunk, a signaling device at saidcentral station, lines connecting said device to said subscribersstations, and means at said subscnbers stations, remotely controlledfromsaid central 1 station, for simultaneously connecting said signalreproducing instruments andsaid'signaling'device.

2. In a program distributing system, a central station, a plurality ofsubscribers stations, pro-gram trunks terminating at said centralstation, each of'said program trunks strument at each'of saidsubscribers s'ta-' being connected to said subscribers stations tionsadapted to be connected byselective switching means to any one of saidlines, a

signaling device at said central station, lines connecting said deviceto said subscrlbers stations, and relay switching means at saidsubscribers stations, remotely controlled from the central station,whereby said signal reproducing instruments may be. simultaneouslyconnected to said signaling device.

3. A program distributing system, a central station from which aplurality rate lines radiate to subscribers stations, signal reproducinginstruments at each subscribers station and meansfor selectivelyconnecting said instruments to any one of of sepa- 1 said lines, anannouncers microphone at said central station, means for lmpressmgspeech signal'reproducinginstruments at said subscrlbers statlonsadapted to be connected by p selectiveswitchmg means to any one of saidlines, an announcers microphone at said central station, means forimpressing speech currents therefrom upon one of said lines, means forimpressing continuous currents upon said selected line, and a relay ateach subscribers station connected to said selected line, adapted to beenergized by said continuous current, to connect the subscribers signalreproducing instrument and said microphone.

5. A program distributing system comprising a central station, programtrunks terminating thereat, a plurality of subscribers stations,separate lines connecting each of said trunks 'to said subscribersstat-ions, signalreproducing intruments at said subscribers stat-ionsadapted to be connected by selective switching means to any one of saidlines, an announcers microphone at said central station, switching meansat said central station 'for connecting one of said lines to saidmicrophone and for simultaneously impressing a battery voltage upon saidline, and arelay at each subscribers station adaptedto be operated uponthe application of said voltage to the selected line to connect thesubscribers signal reproducing instruments and said microphone.

In witness whereof, I hereunto subscribe my name this 25thday ofFebruary A. D.,

JOHN J. KUHN.

